ABSTRACT Calcium homeostasis is of crucial importance for the function of cardial myocytes in normal electrical and mechanical processes. The sarcoplasmic reticular Ca-ATPase and the sar-colemmic Na/Ca exchanger contribute mainly to the steady state of calcium in the myoplasm. The Na/Ca exchanger serves as the principal calcium extrusion mechanism and regulates calcium content of the sarcoplasmic reticulum by regulating the resting [Ca2+]i level, through which the Na/Ca exchanger regulates the force of contraction sequentially. Very small calcium entry can trigger significant sarcoplasmic reticular calcium release (CICR). During the upstroke and plateau phasesof the action potential, There is evidence that indicates Ca2+ influx via the Na/Ca exchanger, and the depolarisation-induced calcium entry on Na/Ca exchange may contribute mainly to triggering intra-cellular calcium release. Na/Ca exchange should be reevaluated as a route through which Ca2+, as a triggering signal, enters cardiac myocyte during excitation-contraction coupling.

Aim To investigate the effects of ?,?-methylene ATP ( ?,?-MeATP) on the P2X1 purino-ceptor-mediated vasoconstriction by different administration ways in the rat mesenteric artery. Methods Isometric vasoconstrictive responses to ?,?-MeATP,administered in non-accumulative manner or single concentration manner,were recorded in the rat isolated mesenteric arterial rings. Results ?,?-MeATP ( 10 -7 ～ 10 -4 mol ? L -1 ) administered in both of the two manners produced concentration-dependent vasocon-strictive responses in the rat isolated mesenteric artery. The vasoconstrictive responses to ?,?-MeATP in single-concentration administration group were greater than those in non-accumulative administration group when the vasoconstriction was standardized either by tissue wet weight or by maximal response to 120 mmol ?L-1 KCl ( P

Objective To discuss pathogenic effects of low high-density lipoprotein cholesterol(HDL-C)on atherosclerosis and thromboembolism,the influences of HDL-C on platelet cytosolic free calcium concentration([Ca2+]i),platelet release reaction products beta-thromboglobulin(?-TG)and platelet factor 4(PF4)were observed in dyslipoproteinemia patients with low HDL-C.Methods i,?-TG and PF4 were measured by fluorescent probe Fura 2-AM and ELISA skills respectively,in 42 patients with low HDLC(LHDL-C)and 25 healthy controls(CONT).Results Compared with those in CONT group,the platelet[Ca2+]i,?-TG and PF4 were all higher in LHDL-C group(all P

Aim To study the effect of blocking adenosine A_1 receptors on BDNF protein expression and the endoplasmic reticulum(ER) content of the rat hippocampus.Methods The effect of DPCPX on BDNF protein expression in granular cells of the rat hippocampus was observed using immunohistochemical method,and the effect of DPCPX on ER in neurons of the rat hippocampus was observed with transmission electron microscope.Results DPCPX(0.1 mg?kg~(-1),ip,15 d) significantly increased the number of BDNF positive cells in hippocampus granular cells.DPCPX(0.5 mg?kg~(-1),ip,15 d) significantly increased both the levels of BDNF protein and the number of BDNF positive cells in hippocampus granular cells(P

The study is to establish an HPLC method using fluorescence detector for the determination of doxazosin enantiomers and investigate their chiral inversion in vitro and in vivo. Ultron ES-OVM was taken as the chiral chromatographic column, and the column temperature was 30 degrees C. Isocratic elution using a mobile phase of phosphate buffer-acetonitrile (85 : 15, v/v) at a flow rate of 0.8 mL x min(-1) was done. The fluorescence detection was set at lambda(Ex) = 255 nm and lambda(Em) = 385 nm. Prazosin was used as the internal standard. (-) Doxazosin or (+) doxazosin added into rat plasma in vitro was determined after incubating in 37 degrees C water bath for 2, 5 and 10 days. (-) Doxazosin or (+) doxazosin was administered orally to the rats for one months. Plasma samples were taken at 8 h after the last administration. A good linear relationship was achieved when the concentration of doxazosin enantiomers was within the range of 4 - 2 000 ng x mL(-1). The average recovery for (-) doxazosin was 99.5% with RSD 3.6%, and for (+) doxazosin was 99.3% with RSD 4.3%. Chiral inversion was observed neither in vitro nor in vivo studies. The method is selective, accurate and reproducible, which is suitable for the detection of doxazosin enantiomers in rat plasma. The in vitro and in vivo studies indicate that chiral inversion occurs uneasily between (-) doxazosin and (+) doxazosin in the rat.

Aim To analyze the blocking effect of ( ± ) doxazosin [ ( ± ) DOX ] , ( -) doxazosin [ ( -) DOX] and ( +) doxazosin [( +) DOX] on the vaso-constriction of rat isolated mesenteric arterioles media-ted by α1-adrenoceptors. Methods The vasoconstric-tion induced by phenylephrine ( Phe) in the rat isola-ted mesenteric arterioles ( the second- and third-order branches) was recorded using DMT wire myograph sys-tem 620M, and theα1-adrenoceptor antagonistic activ-ity of ( ± ) DOX and its enantiomers was analyzed. Results The inner diameter of second- and third-or-der branches of the rat mesenteric artery was (162. 5 ± 5. 3) μm (n=11) and (103. 1 ± 2. 3) μm (n=23), respectively. The values of normalized preload of the second-and third-order branches, which were calculat-ed by the LabChart software, were (2. 93 ± 0. 51) mN ( n =11 ) and ( 2. 64 ± 0. 50 ) mN ( n =23 ) ( P >0. 05 ) . Vasoconstrictive responses to Phe in the sec-ond-order branche of rat mesenteric artery under nor-malized preloads were not significantly different from those under 5 mN preload;however, the Emax values of the Phe-induced vasoconstriction under 10 mN, 15 mN and 20 mN preloads were decreased by 12%, 29%and 43% ( P<0. 01 ) respectively compared with those under normalized preload. The concentration-response curves for Phe were shifted to right in a concentration dependent manner by ( -) DOX or ( +) DOX at 0. 001 , 0. 01 and 0. 1 μmol · L-1 without significant change in their Emax values in the second-and third-or-der branches of rat mesenteric artery. Schild plot anal-ysis indicated that ( -) DOX, ( +) DOX and ( ± ) DOX non-competitively inhibited the vasoconstrictive responses to Phe in the second-order branches, and the rank order of pKB values was ( +) DOX ( 8. 67 ± 0. 10 ) , ( ± ) DOX ( 8. 53 ± 0. 090 ) , ( -) DOX (7. 85 ± 0. 09). However, schild plot analysis indica-ted that ( -) DOX and ( +) DOX competitively inhibi-ted the vasoconstrictive responses for Phe in the third-order branch, and the rank order of their pKB values was ( ± ) DOX ( 8. 68 ± 0. 17 ) , ( +) DOX ( 8. 48 ± 0. 10 ) , ( -) DOX ( 7. 48 ± 0. 140 ) . Conclusion The α1-adrenoceptor blocking activity of ( -) DOX is much weaker than that of ( +) DOX or ( ± ) DOX in the rat isolated mesenteric arterioles, and there is a tendency to enhance the activity of ( ± ) DOX in third-order branches of the rat mesenteric artery though theα1-adrenoceptor blockade effect of ( ± ) DOX is not significantly different from ( +) DOX.

Objective To explore the factors related with difficulty of laparoscopic cholecystectomy(LC) for acute calculus cholecystitis.Methods A total of 245 patients were retrospectively divided into two groups:easy group(123patients)and difficult group(122patients,including 32patients of conversion to OC)based on surgery time and LC or OC.Results There were statistical differences between the groups in regards to preoperative body temperature,white blood cell count,surgical timing,the thickness of gallbladder wall,gallbladder volume,and diameter of common bile duct(all P

a adrenoceptor-mediated increases in smooth muscle tone of the prostate gland and urethra acts as a dynamic factor for BPH-related obstruction of the urethra, a1 adrenoceptor antagonists are considered as the first-line therapy for the patients with BPH. The search for selective a1A a-drenoceptor antogonists with high uroselectivity is strategical for drug discovery research.

Objective To discuss the therapeutic effects of rhubarb and natrii sulfas for severe acute(pancreatitis)(SAP).Methods Eighty-three patietns with SAP were randomly divided into treatment group(group A,n=45) and control group(group B,n=38).The 2 groups received the same therapy except that group A received rhubarb and natrii sulfas through nasogastric tube.Results In treatment group(compared) to control group,the clinical symptoms such as abdominal pain and distention were more quickly(relieved),with early return to oral food intake,lesser complications and shorter hospital stay(all with P

Aim To study the mechanisms of inotropic responses to doxazosin enantiomers in the isolated rat atrium.Methods We analyzed the positive inotropic response to (-)doxazosin and the negative inotropic response to (+)doxazosin in the left atrium of rat u-sing receptor-pharmacological technique.Results In the preparation treated with verapamil,the positive in-otropic responses to 3 μmol·L-1 (-)doxazosin were significantly inhibited from the control level (245.7 1 ± 44.29)mg to (172.50 ±43.34)mg,(P<0.05).In the preparation treated with methylene blue,the posi-tive inotropic responses to 3 μmol·L-1 (-)doxazosin were significantly potentiated from the control level (245.7 1 ±44.29 )mg to (303.33 ±45 .90 )mg,(P<0.05 ).In the preparation treated with H-89 ,the positive inotropic responses to 3,10 and 30 μmol · L-1 (-)doxazosin were (338.57 ±96.86 ) mg, (471.43 ±107.61)mg and (520.00 ±103.44)mg, which were significantly (P<0.05 ~0.01)larger than the control levels of (245.71 ±44.29)mg,(314.29 ±90.34)mg and (357.14 ±68.49 )mg.Treatment with phenoxybenzamine,atropine,propranolol or indo-methacin did not significantly affect the responses to doxazosin enantiomers.Conclusion The positive ino-tropic responses to (-)doxazosin in the isolated left a-trium of rat are partially involved in L-type Ca2+chan-nels and intracellular cGMP level.However,α-adre-noceptors,muscarinic receptors,β-adrenoceptors and cyclooxygenases are not related to the responses to doxazosin enantiomers.